Speech recognition is the process by which an acoustic signal received by microphone is converted to a set of text words, numbers, or symbols by a computer. These recognized words then can be used in a variety of computer software applications for purposes such as document preparation, data entry, and command and control. For example, speech recognition systems may be used in modern operating rooms to control various medical systems and devices. A surgeon or other user, by giving a simple voice command, may direct the functionality of a device controlled by the speech recognition system. For example, the surgeon may deliver a voice command to adjust a patient table or adjust the pressure of a pump.
To enable speech recognition or voice-driven device control in an operating room, medical devices and/or other equipment are connected with a component (e.g., a call system) through communication channels (e.g., an Ethernet connection, device bus, etc.). A speech recognition application is also connected, providing the voice driven user interface and recognition software. When a voice command is issued, the command may be recognized and converted to a text string. If it is successfully identified as valid command corresponding to one of the connected devices or applications, the system will send an appropriate signal so that the desired control action is taken.
Control systems, and particularly speech or voice-driven control systems, often do not provide 100% command accuracy. Excluding human error, errors in speech recognition and control systems may be categorized into three classes: deletion error, substitution error, and insertion error. An example of deletion error is when the speech recognition system fails to identify a valid command correctly and rejects the valid command as an out-of-vocabulary input. A substitution error occurs, for example, when a valid command is issued but the speech recognition system incorrectly identifies the command and produces a result in accordance with another command in the system's vocabulary. An insertion error occurs, for example, when an out-of-vocabulary input, such as a human utterance or a background noise, is mistakenly identified as a command. In an operating room setting where accuracy is critical, such inaccuracies are highly undesirable and potentially life threatening.
When such errors occur, prior art systems generally lack means for a user to take immediate action to mitigate the hazard. For example, prior art speech recognition and control systems have an inherent time delay. Typically such systems must wait to receive and process a complete utterance prior to producing a result. Therefore, it is difficult for a user to take immediate action to prevent a hazard when an error is realized. Further, in the case of errors caused by a continuous background noise, such systems are often blocked from receiving valid voice commands until the background noise ceases.
It is therefore desired to provide a speech recognition system and method which overcomes the above-described problems associated with prior art systems.